Has it been established that any skydiving injury or fatality has ever been attributed to a hoodie?

At one time people like you said the same thing about rigid wingsuits, snaggy camera mounts, outward protruding ripcord handles, solid cone pin closures, boot lace hooks, non-tapered container flaps, flap stiffeners, anti-wind blast handles, kevlar lines, free-packing without a deployment bag, no riser covers, belly-mounted pilot chutes, capewell riser releases and other things that at the time they could not imagine possibly causing problems. But they all eventually did.

If it's unnecessary and serves no beneficial purpose, then why risk it?

But go right ahead and wear a hoodie if you want. Maybe you'll be lucky and nothing bad will happen. But that won't prove that something bad cannot happen. Then again, maybe you'll be the first to die from a hoodie/reserve pilot chute bridle entanglement.

Hey, maybe you could also jump with a machete as a hook knife. I've never heard of anyone dying from having a machete on their gear, so I'm sure it's perfectly safe.